The pinion nut is a funny thing. It's "ovaled" to help make it self locking and when you take one off you're supposed to use a new one.
Once the pinion and flange/yoke are off you can pry out the seal with no problem and put another in.
But then you have to torque the pinion nut and here I'm unsure of how Dana 35's work. In the Ford 7.5/8.8 rear there is a "crush sleeve" which you have to compress and you should replace it generally if you take the flange/yoke off.
Now, compressing it in the rear is a wierd procedure: you have to torque it down with the pinion immobilized, then free it up and check how much force it takes to rotate the pinion (and it's a small amount). If it's not right, you have to retorque.
The catch: it takes like 350 lb/ft to torque the bloody thing!
So, there is some labor involved, and some specialty tools like low range torque wrenches (lb/in) and such.
Again, I know the Ford rears only, but I'm sure the Dana probably is something like it and requires similar attention to detail.
John Griggs -- Kennett Square, PA
2002 Ranger 4x4, SAS'd, with too many other mods...
good information. i think i can handle the job, just want to get the most info i can.
The Dana 35 uses a similar procedure to what John outlined for the rear axles. There is no torque spec for the pinion nut itself. The torque spec is for the rotational drag on the pinion bearings in pound-inches. If you mistakenly exceed that torque by overtightening the nut, you must start over with a new crush sleeve.
You will need a way to apply a lot of torque on the pinion nut and a way to hold the yoke while you're doing that. The factory holding tool is basically a long arm that bolts to the flange. There is also a special seal extractor tool but I would think you could do without it if you're careful.
I take it you're out of warranty, cuz the samething happened to me earlier this year. I posted on it too. It seems A LOT of us had same probelm, if you are out of warranty try arguing that it shouldn't have failed or its recalled or something...it won't cost you anything to try!
Of course it's Murphys Law that the cheapest part will fail that which requires an extraordinary about of labor to replace...is the part that will fail!
I have been through one, already, they did mine under warrentee, I think i had like 12K miles on it. Of course I took it to the dealer by friend works at and he said there was all kinds of sand and dirt inbetween the front driveshaft and the diff housing. So that sand and dirt was sitting in there acting like sandpaper on the back of the seal. It was just a matter of time before it started leaking. Now I make sure to take extra care to wash that crap out after wheeling.